Electrolytic process for producing alloys of lithium



March 14, 1933. H, OSBORG 1,901,407

ELECTROLYTIC PROCESS FOR PRODUCING ALLOYS OF LITHIUM Filed June 5, i931INVENTOR. EZZ7Z6' Osorg,

A TTORN E YS.

Patented Mar. 14, 1933 HANS osnoas, or raANxron'r-oN-rHn-m m, GERMANY,

ELECTROLYTIC PROCESS FOR PRODUCING ALLOYS F LITHIUM Application filedJune 5, 1931, Serial No. 542,460, and in Germany June 6, 1930.

The present invention relates to an electrolytic process for producingalloys of lithium and more particularly to the electrolytic process ofproducing alloys of lithium and a metal fusing at a high temperature,particularly a heavy metal.

It is well known, that the properties of certain metals may beinfluenced by the addition of metallic lithium to molten baths of saidmetals. The addition of lithium to molten baths of metals such asnickel, iron, etc., or alloys thereof, has been found to beobjectionable for various reasons. stance, metallic lithium floats 9nthe surface of the molten metal because of its low specific gravity andburns or vaporizes on the surface of the bath because of its low boilingpoint and of its easy combust-ibility. All of the aforesaidobjectionable reactions occur before the lithium has had an opportunityof reacting, or alloying with the metal or alloy inthe molten bath whichis undergoing treatment. It has been impractical consequentl v tointroduce more than a few tenths of one per cent of metallic lithiuminto molten baths of metals or alloys, particularly those having highermelting points. Even the addition of relatively small quantities ofmetallic lithium to molten metal baths involves considerable loss of therelatively expensive metallic lithium. For the aforesaid reasons, aswell as others, it has been unsatisfactory and impractical to utilizemetallic lithium on a commercial and industrial scale.

The present im'entioi contemplates a method of producing lithium in theform of alloys which can be used on a practical and an industrial scalewithout beingsubjected 40 to the disadvantagesnoted hereinabove.

It is another object of the invention to provide an electrolytic processof producing alloys of lithium and a metal, especially a heavy metal, ina practical, satisfactory,. economical and commercial manner.

For in- It is a further object 'of the invention-to provide anelectrolytic process for producingalloys of lithium and a metal,especially a heavy metal, in such a manner that the lithium and othermetal is deposited simultaneously at the cathode.

The invention also contemplates providing an electrolytic process ofproducing an alloy of lithium and a metal in such a manner that theproportion of lithium to the other metal which is deposited at thecathode may be controlled and regulated.

Other objects and advantages of the invention will become apparent fromthe following description.

Broadlyv stated, the invention contemplates utilizing plates, sheets,bars, rods, or the like of the metal to be deposited and alloyed withlithium, and arranging said plates, sheets, bars, rods orthe like insuch a relation to a graphite anode or anodes that when current ispassed through a fused electrolytic bath, an alloy of lithium and themetal is deposited at the cathode, preferably in the form of an alloyhaving a certainpercentage oflithium and a certain percentage of theother metal.

' For the urpose of facilitating an understanding oi the invention bythose skilled in. the art, the following specific illustrative exampleis given. It is to be noted, however, that the specific example ismerely illustrative and the invention is not to be limited thereby.

The following description is taken in conjunction with the accompanyingdrawing in which Fig. 1 represents a sectional elevational view,somewhat diagrammatic, of an electrolytic cell in which my invention maybe car- 5 ried out; and

Fig. 2 illustrates a sectional view, somewhat diagrammatic, taken on theline 2-2 of Fig. 1.

For the purpose of producing an alloy of lithium and nickel, forinstance, an anode is in an electrical connection via lines L containinga resistance R and ammeter A with the graphite anode or anodes. Byregulating the area of the graphite plates to the area of the nickelrods, and the resistance It used in a connection between the nickel rodsand the graphite plates, it is possible to control and re ulate theamount of current passing from the graphite anodes and the nickel anodesto the cathode, as one skilled in the art will readily understand. Forinstance, if 2500 amperes were being passed through the anode the nickelrods and graphite plates could be arranged so that 150 amperes wouldpass through the nickel or metal rods and the other 2350 amperes wouldpass through the graphite plates. The 150 amperes would effect thedeposition of a certain amount of metal whereas the 2350 amperes wouldeffect the deposition of a certain amount of lithium. By calculating theamount of lithium and the other metal deposited by the aforesaidcurrents, it is possible to determine the composition of the lithiumalloy to be deposited at the cathode C.

In carrying the present invention into practice, it is preferable to usean electrolytic cell, such as illustrated in Figs. 1 and 2, having ahollow anode preferably in the form of a square shell, the sides ofwhich are graphite plates and the corners of which are nic el rodsconnected in parallel with the graphite plates. A resistance may beincorporated in the connection between a nickel rod and an adjacentgraphite plate in order to further control the amount of current passingthrough and from the nickel rods and through and from the graphiteplates. A cathode, such as a nickel rod may be located in the center ofthe hollow square anode. Into the cell a molten electrolyte may bepoured and then a suitable electric current may be turned on to causethe deposition of a lithium alloy. Usually a halide of lithium or amixture of halides may be employed as the electrolyte. Potassiumchloride, or other appropriate salts, may be added to such anelectrolyte for the purpose of facilitating the electrolysis and thedeposition of the lithium alloy, or for other purposes. Of course, it ispossible to use compounds other than halides. provided such compoundsare capable of being transformed into halides or into compounds suitablefor the electrolytic deposition of the lithium and the other metals whenthe current is passed through the electrolytic cell containing suchcompounds in a fused state. For exam le, xides, hydroxides, carbonatesand the likerrziy be added to the electrolytic bath because the chlorineelectrolytically evolved at the anode will transform such oxides, etc.into chlorides. In some instances, it may be advantageous to add suchoxides, etc., or mixtures thereof to the fused electrolytic bath in theform of briquettes.

In some cases, it is preferable to add a mixture of the lithiumelectrolyte, say lithium chloride and potassium chloride, with enough ofa compound, say the chloride'of the other metal or metals to bedeposited simultaneously with the lithium at the oathode. By adjustingthe composition of the bath, an alloy of lithium of the desiredcomposition may be electro-deposited, as one skilled in the art willreadily understand. When the electro-deposition of the alloy commences,the'metal or'metals to be deposited with lithium willgo into solutionfrom the metal rods connected in parallel with the graphite plates. Inthis manner, if all of the operating conditions are correctly selected,alloys of the desired composition may be obtained even from the verybeginning of the electrolysis. The ratio of the surfaces or areas of thegraphite plates and the metal rods in the anode have to be adjusted sothat the proper amount of lithium and the said metal or metals can beplated simultaneously at the cathode. By

controlling or regulating the graphite and metal areas of the anodeand/orthe resistance in the parallel connection between the graphiteplates and the metal rods, it is possible to cause the deposition oflithium alloys of a desired or selected composition.

Lithium alloys of certain metals when deposited at the cathode in amanner set forth hereinabove, rise to the surface of the fused or moltenbath, when the lithium content of such an alloy is relatively high. Inthese cases, the lithium alloy can be skimmed off the surface of thebath like pure lithium by means of suitable utensils, such as ladles orthe like. In other cases, particularly alloys having low lithiumcontent, the alloy deposited has a relativelyhigh specific gravity andis more or less soft. The deposited alloy sticks to the surface of thecathode from which it can be easily scraped off by means of suitabletools. As a general rule, in order to prevent contamination of the alloyby foreign metals, it will in general be advisable to select the cathodeof a metal which is a component of the lithium alloy to beelectro-deposited. Thus, for example. it is advantageous to employ anickel cathode when producing a lithium-nickel alloy. In case alithium-iron alloy is to be produced. then a low carbon steel cathode isemployed. In this manner, a relatively pure alloy of lithium can bedeposited at the cathode. Of course. when the deposited lithium alloy isskimmed off the molten electrolyte, or is removed from the cathode in aspongy condition, a portion of the electrolyte may be contained in thealloy. In these cases, as one skilled in the art will readilyunderstand, the lithium alloy may be purified in any well known manner,such as by remelting under a salt or equivalent cover.

It will be appreciated that in accordance with the present invention, itis possible to produce alloys of lithium with heavy metals having acontent of lithium which exceeds by far the lithium content in oldindustrial alloys containing lithium. These old alloys contained only afew tenths of one per cent of lithium. \Vith the production of lithiumalloys, it is possible to produce prealloys which are rich in lithiumand which preferably contain more than 3% thereof.

Such alloys with a high lithium content may be used advantageously inindustry.

The present invention may be carried into practice in a variety of ways,but the following specific example is given so that one skilled in theart can carry the present invention readily and quickly into practice.

An electrolytic cell is provided with a hollow anode of a square orrectangular cross section. The anode is constructed so that the sidesconsist of graphite plates and the corners consist of nickel rods. Thecathode may consist of a nickel rod. The electrolyte preferably consistsof a melted mixture of lithium chloride and potassium chloride. Theanode and cathode may have any suitable size but I prefer to use nickelrods which are about 10 to about 25 millimeters in thickness. The nickelrods may be connected in parallel with the graphite plate in anysuitable manner as long as they do not form an arc with parts of thegraphite plates. In other words, in a cell having a hollow square anode,for example, the graphite portions of said anode do not cover each sideentirely and the metal rods can be installed in the corners of the anodewithout any interference of current lines emanating from the anode.

By passing a suitable electric current, say about 1550 amperes and 1480amperes through the graphite and nickel anodes, respectively, or sayabout 1550 amperes and 600 amperes through the graphite and metalanodes, respectively, alloys of different percentages are deposited atthe cathode. The nickel alloy thus obtained contains about 20% or about40%, respectively, of lithium. It is also possible of course to obtainan alloy with a higher as well as a lower lithium content. The alloy mayrise to the surface of the electrolyte or it may stick to the cathode ina spongy or granular form. The deposited lithium-nickel alloy may beremoved in any appropriate manner as mentioned hereinabove. By remeltinthe deposited alloy at a temperature of a out 400 with lithium intopractice by utilizing any other appropriate and equivalent metals andsubstances. For instance, instead of nickel, cobalt, manganese, gold,platinum, silver, copper, iron and the like may be'employed' A metal ofthe foregoing type shall be designated in the specificationand claims asa metal melting at a relatively hi h temperature above about 600 C. Asto urther variations of the invention it is to be observed that theresent process contemplates the production 0 alloys the components ofwhich have decomposition voltages which are quite far apart in theelectromotive series such as lithium or the like and nickel or the like.These components are deposited simultaneously at the cathode in selectedproportions by passing an electric current through a nickel anode or thelike and a graphite anode of a cell con-- taining a bath .in which acompound containing lithium or the like (i. e. a metal moreelectronegative than nickel or the like). By regulating the electriccurrent passing through the nickel anode and the graphite anode to suchamounts that the equivalent of the anions deposited at the graphiteanode correspond to the equivalent of the more electronegative metal.(lithium) deposited at the cathode while the e uivalent of the anionsdeposited at the nic e1 (less'electronegative metal) anode correspond tothe equivalent of nickel (or other less electronegative metal) depositedsimultaneously (or other more electronegative metal) at the cathode. Itis obvious'that selected or pre-determined proportions of lithium (orother more electronegative metal) and of nickel (or other lesselectronegative metal) may be simultaneously deposited at the cathode byregulating the electric current in the foregoing manner.

The terminology used herein (electronegative etc.) is in accordance withmodern practice. For instance, such practice and terminology isdescribed in textbooks, such as Bllllll and Hogaboonis Principles ofElectroplating (published by McGraw-Hill Company, New York).

I claim:

1. The process of producing a lithium alloy containing a metal meltingat a relatively high temperature above about 600 C., which comprisesestablishing an electrolytic cell having a fused bath containing alithlum compound capable of permitting the electroto beelectro-deposited, and passing an electric current through said cell viasaid graphite anode and said metal anode to cause the deposition of anallo of lithium and the said metal at the catho e 2. The process ofproducing a lithium alloy containing a metal melting at a relativelyhightemperature above about 600 0., such as set forth in claim 1, inwhich the lithium and the metal are deposited simultaneously in the formof an alloy at the cathode.

3. The process of producing adithium alloy containing a metal melting ata relatively high temperature above about 600 C., such as set forth inclaim 1, in which the areas of the graphite and metal portions of theanode are so selected that the ratio of the amount of lithium and theamount of other metal to be deposited at the cathode can be controlled4. The process of producing a lithum alloy containing a metal melting ata relatively high temperature above about 600 0.,

' metal or metals to be de osited with lithium stances containing themetals to be deposited with lithium are added to the electroylte in sucha condition as to be capable of being transformed into compounds capableof ermitting'the metals to be electro-depositedtherefrom.

6. The process of producing a lithium alloy containing a metal meltingat a relatively high tem rature above about 600 (1., such as set fort inclaim 1, in which a compound of lithium or a metaltto be roduced isadded to the fused electrolyte efore or during electrolysis and is ofsuch a constitution as to be capable of being converted into a chlorideby the action of chlorine liberated at the anode.

7. The process of producing an alloy, such as a lithium alloy, by theelectrodeposition of a more electronegative metal (lithium) and a lesselectronegative metal (nickel) atthe cathode of an electrolytic cellwhich comprises establising a fused 'electrolytic bath containing acompound of a more electronegative metal (lithium) and a plurality ofanodes including a graphite anode and an anode of a less electronegativemetal (nickel), passing an electric current through said cell, andregulating the current passing through said graphite anode and metalanode to such amounts that the equivalent of the anions deposited at thegraphite anode correspond to the equivalent ofthe more electronegativemetal (lithium) demy hand.

HANS OSBORG.

